tbaeder created this revision.
tbaeder added reviewers: tstellar, sfantao, tejohnson.
Herald added subscribers: cfe-commits, steven_wu, hiraditya, inglorion, mgorny.
Herald added a project: clang.
tbaeder requested review of this revision.
After setting the LTO mode from the -flto option, look at the input files as
well. If any of them is an object file containing LLVM bitcode,
set the LTO mode to either thin or full, depending on the input file.
This makes the following sample work:
clang test.c -c -flto
clang test.o
Which also works when using GCC. Currently this makes non-lld linkers print an
error, for example when using ld.bfd:
$ clang test.o
test.o: file not recognized: file format not recognized
clang-10: error: linker command failed with exit code 1 (use -v to see
invocation)
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D90457
Files:
clang/include/clang/Driver/Driver.h
clang/lib/Driver/CMakeLists.txt
clang/lib/Driver/Driver.cpp
clang/test/Driver/thinlto_backend.c
Index: clang/test/Driver/thinlto_backend.c
===================================================================
--- clang/test/Driver/thinlto_backend.c
+++ clang/test/Driver/thinlto_backend.c
@@ -24,3 +24,13 @@
// RUN: not %clang -O2 -o %t1.o %s -c -fthinlto-index=%t.thinlto.bc 2>&1 \
// RUN: | FileCheck %s -check-prefix=CHECK-WARNING
// CHECK-WARNING: error: option '-fthinlto-index={{.*}}' requires input to be LLVM bitcode
+
+// thinlto enabled without -flto=thin explicitly passed
+// RUN: %clang -O2 %s -c -flto=thin -o %r.o
+// RUN: %clang %r.o -### 2>&1 | FileCheck %s -check-prefix=CHECK-THIN-LTO-ENABLED
+// CHECK-THIN-LTO-ENABLED: -plugin-opt=thinlto
+
+// Same for full LTO
+// RUN: %clang -O2 %s -target x86_64-unknown-linux-gnu -c -flto=full -o %r.o
+// RUN: %clang %r.o -### 2>&1 | FileCheck %s -check-prefix=CHECK-FULL-LTO-ENABLED
+// CHECK-FULL-LTO-ENABLED: LLVMgold
Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -64,6 +64,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
@@ -586,6 +587,43 @@
return Target;
}
+static LTOKind
+getInputLTOMode(const std::pair<types::ID, const llvm::opt::Arg *> Input) {
+ // Must be an object file
+ if (Input.first != types::TY_Object)
+ return LTOK_None;
+
+ // ... and contain LLVM bitcode
+ for (const char *Filename : Input.second->getValues()) {
+ auto Buff = llvm::MemoryBuffer::getFile(Filename);
+ if (Buff) {
+ auto R = (*Buff)->getMemBufferRef();
+ Expected<llvm::BitcodeLTOInfo> LTOInfo = llvm::getBitcodeLTOInfo(R);
+
+ if (LTOInfo)
+ return LTOInfo->IsThinLTO ? LTOK_Thin : LTOK_Full;
+
+ llvm::consumeError(LTOInfo.takeError());
+ }
+ }
+
+ return LTOK_None;
+}
+
+void Driver::setLTOModeFromInputFiles(const InputList *Inputs) {
+ if (LTOMode != LTOK_None)
+ return;
+
+ for (auto Input : *Inputs) {
+ auto InputLTOMode = getInputLTOMode(Input);
+
+ if (InputLTOMode != LTOK_None) {
+ LTOMode = InputLTOMode;
+ break;
+ }
+ }
+}
+
// Parse the LTO options and record the type of LTO compilation
// based on which -f(no-)?lto(=.*)? option occurs last.
void Driver::setLTOMode(const llvm::opt::ArgList &Args) {
@@ -1164,6 +1202,8 @@
InputList Inputs;
BuildInputs(C->getDefaultToolChain(), *TranslatedArgs, Inputs);
+ setLTOModeFromInputFiles(&Inputs);
+
// Populate the tool chains for the offloading devices, if any.
CreateOffloadingDeviceToolChains(*C, Inputs);
Index: clang/lib/Driver/CMakeLists.txt
===================================================================
--- clang/lib/Driver/CMakeLists.txt
+++ clang/lib/Driver/CMakeLists.txt
@@ -3,6 +3,7 @@
Option
ProfileData
Support
+ BitReader
)
if(WIN32)
Index: clang/include/clang/Driver/Driver.h
===================================================================
--- clang/include/clang/Driver/Driver.h
+++ clang/include/clang/Driver/Driver.h
@@ -578,6 +578,10 @@
/// compilation based on which -f(no-)?lto(=.*)? option occurs last.
void setLTOMode(const llvm::opt::ArgList &Args);
+ /// Parse the \p Inputs list for LTO inputs. LTO inputs are object files
+ /// that contain LLVM bitcode
+ void setLTOModeFromInputFiles(const InputList *Inputs);
+
/// Retrieves a ToolChain for a particular \p Target triple.
///
/// Will cache ToolChains for the life of the driver object, and create them
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